let app_container = document.getElementById('app-container');
app_container.style.height = window.innerHeight + 'px';
app_container.style.width = window.innerWidth + 'px';
window.onresize = function () {
    app_container.style.height = window.innerHeight + 'px';
    app_container.style.width = window.innerWidth + 'px';
};